- In a small saucepan, heat water and lime juice.
- Once heated, stir in gelatin, and continue to stir until completely dissolved.
- Pour gelatin mixture into a large mixing bowl, allowing to cool, about 2 minutes.
- Add yogurt and lime zest to gelatin mixture, and then beat with an electric mixture.
- Once mixed, fold in whipped topping.
- Pour entire mixture into graham cracker crust and chill until firm, about 1 hour.
- Garnish with lime slices.